ML073520248

Technical Specification Bases (Tsb) Change

ML073520248
Person / Time
Site:	Oconee
Issue date:	12/12/2007
From:	Brandi Hamilton Duke Energy Carolinas, Duke Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML073520248 (9)

Text

. 4 BRUCE H HAMILTON Vice President Ah*Energy' Oconee Nuclear Station Duke Energy Corporation ONO] VP / 7800 Rochester Highway Seneca, SC 29672 864 885 3487 864 885 4208 fax bhhamilton@duke-energy.com December 12, 2007 U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk

Subject:

Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC Oconee Nuclear Station

-Docket Numbers 50-269, 270, and 287 Technical Specification Bases (TSB) Change On December 4, 2007 Station Management approved revisions to TSB 3.3.18, EPSL Voltage Sensing Circuits, to state that Oconee Unit 1 Standby Bus #1 and Bus #2 voltage sensing circuits are required in order for Oconee Units 1, 2, and 3 Standby Bus #1 and #2 voltage sensing circuits to be considered OPERABLE.

Attachment 1 contains the new TSB pages, Attachment 2 contains the marked up version of the TSB pages.

If any additional information is needed, please contact Reene Gambrell at 864-885-3364.

Very truly yours, B. H. Hamilton, Vice President Oconee Nuclear Site www. duke-energy. com

Attachment #1 Proposed Bases revision Remove Page Insert Page B 3.3.18-1 B 3.3.18-1 B 3.3.18-2 B 3.3.18-2 B 3.3.18-3 B 3.3.18-3 B 3.3.18-4 B 3.3.18-4

EPSL'Voltage Sensing Circuits B 3.3.18 B 3.3 INSTRUMENTATION B 3.3.18 Emergency Power Switching Logic (EPSL) Voltage Sensing Circuits BASES BACKGROUND The EPSL voltage sensing circuits for the Startup Transformer, Standby Bus #1, Standby Bus #2, and the Auxiliary Transformer provide input to the EPSL controls to actuate breakers and initiate transfer control sequences.

Each phase of each source has an individual potential transformer feeding a 2 out of 3 logic for determining the status of the power source. The voltage sensing circuits also provide trip signals to the breaker control circuitry for the normal incoming breakers (N breakers), startup incoming breakers (E breakers), and CT-5 incoming breakers (SL breakers) whose trip is from Unit 1 Standby Bus #1 ,-Standby Bus #2 voltage sensing circuits only.

The EPSL system is designed to ensure power is supplied to the main feeder buses (MFBs) during a LOCA. In order for itto perform this function, the voltage sensing circuits for the Startup Transformer, Auxiliary Transformer, Standby Bus #1, and Standby Bus #2 must be OPERABLE.

These voltage sensing circuits provide input to the EPSL transfer functions.

The transfer functions utilize the voltage sensing circuits to initiate breaker Operations to ensure the MFBs are connected to an energized source (startup or standby). The N and E breakers also get direct trips from the two-out-of-three logic.

If a loss of power occurs on the Standby Bus when a Lee Combustion Turbine or the Central Switchyard is aligned to the Standby Bus, the Oconee Unit 1 Standby Bus #1 and Standby Bus #2 voltage sensing circuits will initiate a transfer of the Standby Bus to the Keowee Unit aligned to the Underground power path. When the CT-5 incoming breakers, (SL breakers) are closed, the Oconee Unit 1 Standby Bus #1 and Standby Bus

1. 2 voltage sensing circuits are required for Oconee Units 1, 2, and 3 Standby Bus #1 and Standby Bus #2 voltage Sensing circuits to be considered OPERABLE.

No protective relay lockouts or inhibits can be present to prevent the connection of required AC power source(s) to the MFBs from the Control Room because their presence will not allow closure of the associated breaker.

APPLICABLE The EPSL voltage sensing circuits are required for the engineered SAFETY ANALYSES. safeguards (ES) equipment to function in any accident with a loss of offsite OCONEE UNITS 1, 2, & 3 B 3.3.18-1 BASES REVISION DATED 12/06/07 1

EPSL Voltage Sensing circuits B 3.3.18 BASES (continued)

APPLICABLE power. The limiting accident for the EPSL voltage sensing circuits is a SAFETY ANALYSES loss-of-coolant accident (LOCA) with a simultaneous loss of offsite (continued) power (Ref. 1).

The EPSL voltage sensing circuits satisfy Criterion 3 of 10 CFR 50.36 (Ref. 2).

LCO Three channels of each EPSL voltage sensing circuit (Auxiliary Transformer, Startup Transformer, Standby Bus #1, Standby Bus #2) are required to be OPERABLE. These circuits and associated channels ensure that no single failure can cause a loss of required ES equipment.

When the SL breakers are closed, Oconee Unit 1 Standby Bus #1 and Standby Bus #2 voltage sensing circuits are required for Oconee Units 1, 2, and 3 Standby Bus #1 and Standby Bus #2 voltage sensing circuits to be considered OPERABLE.

The LCO is modified by two Notes. Note 1 removes Auxiliary Transformer voltage sensing requirements when both N breakers are open. The function of the Auxiliary Transformer Voltage Sensing circuits is to provide a trip signal to the N breakers. When the N breakers are open, the Auxiliary Transformer voltage sensing circuits are not required and, therefore, need not be OPERABLE. Note 2 requires only the EPSL voltage sensing circuits associated with required AC power source(s) to be OPERABLE when not in MODES 1, 2, 3, and 4.

APPLICABILITY The EPSL voltage sensing circuits are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure that power is provided from AC Sources to the AC Distribution system within the time assumed in the accident analyses.

The EPSL voltage sensing circuits associated with required AC power source(s) required to be OPERABLE in MODES 5 and 6 and during movement of irradiated fuel assemblies provide assurance that:

a. Systems needed to provide adequate coolant inventory makeup are available for the irradiated fuel assemblies;

b. Systems needed to mitigate a fuel handling accident are available;

c. Systems necessary to mitigat'e the effects of events that can lead to core damage during shutdown are available; and OCONEE UNITS 1, 2, & 3 B 3.3.18-2 BASES REVISION DATED 12/06/07 I

EPSL Voltage Sensing circuits B 3.3.18 BASES (continued)

APPLICABILITY d. Instrumentation and control capability is available for monitoring (continued) and maintaining the unit in a cold shutdown condition or refueling condition.

ACTIONS A Note has been added to the ACTIONS indicating separate Condition entry is allowed for each Voltage Sensing Circuit.

A.1 If one required channel is inoperable in one or more voltage sensing circuits, it must be restored to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. With one channel inoperable, the remaining two channels are capable of providing the voltage sensing function. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time is considered appropriate based on engineering judgement taking into consideration the time required to complete the required action.

Required Action A.1 is modified by a Note which indicates that the Completion Time is reduced when in Condition L of LCO 3.8.1. Condition L limits the Completion Time for restoring an inoperable channel to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> when emergency power source(s) or offsite power source(s) are inoperable for extended time periods or for specific reasons.

B.1 and B.2 With the Required Action and associated Completion Time not met in MODES 1, 2, 3 and 4, the unit must be brought to a MODE in which the LCO does not apply. To achieve this status, the unit must be brought to at least MODE 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to MODE 5 within 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to allow for a controlled shutdown.

C.1 and C.2 With two or more channels of a required circuit inoperable when not in MODES .1, 2, 3, and 4 or the Required Action and associated Completion Time not met when not in MODES 1, 2, 3, and 4, the affected AC power sources(s) must be declared inoperable immediately. The appropriate Required Actions will be implemented in accordance with LCO 3.8.2, "AC Sources -Shutdown."

OCONEE UNITS 1, 2, & 3 B 3.3.18-3 BASES REVISION DATED 12/06/07 1

EPSL Voltage Sensing circuits B 3.3.18 BASES (continued)

ACTIONS D.1 (continued)

With the Required Action and associated Completion Time not met during movement of irradiated fuel assemblies, movement of fuel assemblies must be suspended immediately. Suspension does not preclude completion of actions to establish a safe conservative condition. This action minimizes the probability or the occurrence of postulated events. The Completion Time of immediately is consistent with the required times for actions requiring prompt attention SURVEILLANCE SR 3.3.18.1 REQUIREMENTS A CHANNEL FUNCTIONAL TEST is performed on each voltage sensing circuit channel to ensure the channel will perform its function. A circuit is defined as three channels, one for each phase. Each channel consists of components from the sensing power transformer through the circuit auxiliary relays which operate contacts in the EPSL logic and breaker trip circuits. Minimum requirements consist of individual channel relay operation causing appropriate contact responses within associated loadshed/breaker circuits, alarm activations, and proper indications for the sensing circuit control power status. The Frequency of 18 months is based on engineering judgment and operating experience that determined testing on an 18 month interval provides reasonable assurance that the circuitry is available to perform its safety function.

REFERENCES 1. UFSAR, Chapters 6 and 15.

2. 10 CFR 50.36.

OCONEE UNITS 1, 2, & 3 B 3.3.18-4 BASES REVISION DATED 12/06/07 1

Attachment #2 Markup of current Bases

EPSL Voltage Sensing Circuits B 3.3.18 B 3.3 INSTRUMENTATION B 3.3.18 Emergency Power Switching Logic (EPSL) Voltage Sensing Circuits 11BASES BACKGROUND The EPSL voltage sensing circuits for the Startup Transformer, Standby Bus #1, Standby Bus #2, and the Auxiliary Transformer provide input to the EPSL controls to actuate breakers and initiate transfer control sequences.

Each phase of each source has an individual potential transformer feeding a 2 out of 3 logic for determining the status of the power source. The voltage sensing circuits also provide trip signals to the breaker control circuitry for the normal incoming breakers (N breakers), startup incoming breakers (E breakers), and CT-5 incoming breakers (SL breakers) whose trip is from Unit 1 Standby Bus #1, Standby Bus #2 voltage sensing circuits only.

The EPSL system is designed to ensure power is supplied to the main feeder buses (MFBs) during a LOCA. In order for it to perform this function, the voltage sensing circuits for the Startup Transformer, Auxiliary Transformer, Standby Bus #1, and Standby Bus #2 must be OPERABLE.

These voltage sensing circuits provide input to the EPSL transfer functions.

The transfer functions utilize the voltage sensing circuits to initiate breaker operations to ensure the MFBs are connected to an energized source (startup or standby). The N and E breakers also get direct trips from the two-out-of-three logic.

If a loss of power occurs on the Standby Bus when a Lee Combustion Turbine or the Central Switchyard is aligned to the Standby Bus, the Oconee Unit 1 Standby Bus 1 and 2 voltage sensing circuits will initiate a transfer of the Standby Bus to the Keowee Unit aligned to the underground power path. When the CT-5 incoming breakers (SL breakers) are closed, the Oconee Unit 1 Standby Bus #1, and Standby Bus

1. 2 voltage sensing circuits are required for Oconee Units 1, 2 and 3 Standby Bus #1, and Standby Bus #2 voltage sensing circuits to be considered operable.

No protective relay lockouts or inhibits can be present to prevent the connection of required AC power-source(s) to the MFBs from the Control Room because their presence will not allow closure of the associated breaker.

APPLICABLE The EPSL voltage sensing circuits are required for the engineered SAFETY ANALYSES safeguards (ES) equipment to function in any accident with a loss of offsite OCONEE UNITS 1, 2, & 3 B 3.3.18-1 Amendment Nos. 300, 300, & 300

power. The limiting accident for the EPSL voltage sensing circuits is a loss-of-coolant accident (LOCA) with a simultaneous loss of offsite power (Ref. 1).

The EPSL voltage sensing circuits satisfy Criterion 3 of 10 CFR 50.36 (Ref. 2).

LCO Three channels of each EPSL voltage sensing circuit (Auxiliary Transformer, Startup Transformer, Standby Bus #1, Standby Bus #2) are required to be OPERABLE. These circuits and associated channels ensure that no single failure can cause a loss of required ES equipment.

The LCO is modified by two Notes. Note 1 removes Auxiliary Transformer both N breakers are open. The voltage sensing requirements when function of the Auxiliary Transformer Voltagebreakers Sensing are circuits open,is to theprovide signal to the N breakers. When the N a trip Auxiliary Transformer voltage sensing circuits are not required and, therefore, need not be OPERABLE. Note 2 requires only the EPSL voltage AC power source(s) to be sensing circuits associated with required OPERABLE when not in MODES 1, 2, 3, and 4.

When the SL breakers are closed, Oconee Unit 1 Standby Bus #1, and Standby Bus #2 voltage sensing circuits are required for Oconee Units 1, 2 and 3 Standby Bus #1, and Standby Bus #2 voltage sensing circuits to be considered operable.